Olav Keerberg is plant physiologist, a specialist in the research area dealing with regulation of the plant leaf CO2 exchange and of the photosynthetic carbon metabolism. In the laboratory of photosynthesis of the Department of Plant Physiology of the Institute of Agricultural and Environmental Sciences of the Estonian University of Life Sciences under his supervision the regulatory processes have been studied on three levels:

dynamic regulation - fast, reversible responses of the biochemical system of photosynthesis to short term changes in the environment;

adaptative regulation - peculiarities and changes in the status of the system caused by growth conditions, which are mostly irreversible and

genetic regulation - changes in the system caused by peculiarities of the genome of the species, by its artificial transformation and by conditions for its expression.

To quantify the parameters of plant leaf CO2 exchange and carbon metabolism the original radiogasometric and radiobiochemical methods have been designed in the laboratory. In recent studies by means of these methods (1) the short-term (cold shock) and long-term (cold acclimation) effects of low temperatures on the photosynthetic carbon metabolism and plant leaf respiration have been elucidated, (2) the parameters of photosynthetic carbon metabolism in different plant species and varieties (starch-deficient versus starch accumulating species, cultivars of wheat with different productivity, species with C3, C4 and C3-C4 type of photosynthesis) have been determined and (3) changes in photosynthetic carbon metabolism induced by genetic modification of the expression of specific photosynthetic enzymes have been ascertained. These studies belong to the research area of metabolomics. On the basis of differences and changes detected in the metabolism the corresponding differences in plant proteome and genome could be predicted.